This present description relates to capacitive membrane transducers. For example, capacitive membrane ultrasound transducers (CMUT) are provided.
CMUTs provide a greater bandwidth than piezoelectric-ceramic transducers. An array of elements, such as a two-dimensional array of elements is formed using microelectromechanical processes. Each element includes a plurality of membranes with associated electrodes separated by a gap or void, which transduce between electrical and acoustic energy. Flexing of the membranes in response to acoustic energy generates an analog electrical signal representing the amount of flexing. However, CMUTs typically have a large impedance mismatch with the receive beamformer electronics due to the low reactance of the CMUT. Receiving an analog signal with a desired dynamic range may use complex, expensive, or large circuits to interface between the CMUT and the receive beamformer. The interface electronics may also require co-location with the CMUT elements, adding to the size, weight, and heat load of the transducer head.